President Barack Obama is likely to announce either Judge Sri Srinivasan or Judge Merrick Garland as his pick for U.S. Supreme Court nominee and the announcement could come as early as Wednesday, a source familiar with the selection process said.

The team of advisers helping to vet candidates, line up their public supporters and answer the president’s questions had finished its work, the source said on Tuesday.

Obama is searching for a replacement for long-serving conservative Justice Antonin Scalia, who died on Feb. 13. With Scalia’s death, the court is divided 4-4 between conservatives and liberals. Obama’s nominee could move the court to the left for the first time in decades.

Republicans, who control the U.S. Senate, have vowed not to hold confirmation hearings or an up-or-down vote on any nominee picked by the Democratic president for the lifetime position on the court. Senate confirmation is required for any nominee to join the bench.

Senate Majority Leader Mitch McConnell has suggested there might be no point even in holding the traditional “courtesy call” meetings with whomever Obama nominates, infuriating Senate Minority Leader Harry Reid and his fellow Democrats.

Republicans, hoping a candidate from their party wins the Nov. 8 presidential election, want the next president, who takes office in January, to make the selection. Billionaire Donald Trump is the leading Republican presidential candidate; Obama’s former secretary of state, Hillary Clinton, is the front-runner on the Democratic side.

Without Scalia, the Supreme Court is evenly split with four liberals and four conservatives. An Obama appointment could tilt the court to the left for the first time in decades.

Both Srinivasan and Garland are seen as having unique attributes that could weigh heavily in Obama’s decision.

Srinivasan, 49, and Garland, 63, serve together on the U.S. Court of Appeals for the District of Columbia Circuit. That appeals court has served as a springboard to the Supreme Court for several justices including Scalia in recent decades.

Srinivasan, who was born in India and grew up in Kansas, would be the first Asian-American and first Hindu on the high court. Obama appointed him to the appeals court in 2013. The Senate confirmed him in a 97-0 vote.

DIVERSITY AN ISSUE

He could appeal to the president’s long-declared interest in bringing more diversity to the bench.

Srinivasan has served in the Justice Department under Democratic and Republican presidents and worked as a clerk to the first woman to serve on the Supreme Court, Sandra Day O’Connor, a Republican appointee.

Garland, who has earned praise from lawmakers of both parties, is the chief judge of the Washington appeals court, where he has served since being appointed by Democratic President Bill Clinton in 1997, winning confirmation in a 76-23 vote. Prior to that, he served in the Justice Department under Clinton.

With Senate Republicans vowing to turn their backs on anyone he picks to fill the vacancy, Obama may be looking for a nominee who could convince the Republicans to change course. Garland could fit that bill with moderate record, background as a prosecutor and a history of drawing Republican support.

Garland was under consideration in 2009 for Obama’s first appointment but the new administration chose Sonia Sotomayor, attracted to her rise from a Bronx housing project to the elite corridors of Yale and the federal judiciary.

Yet they also regarded Garland as a future compromise choice if another vacancy opened in an election year with the Senate under Republican control, according to Obama advisers at the time and others weighing in on the current nomination.

That is the situation now confronting Obama.

Presidents tend to pick nominees younger than Garland, so they can serve for decades and extend a president’s legacy. But Obama may reason that the choice of an older nominee might also entice Senate Republicans into considering Obama’s selection.

Obama already has named two justices to the Supreme Court: Sotomayor, who at 55 became the first Hispanic justice in 2009, and Elena Kagan, who was 50 when she became the fourth woman to ever serve on the court in 2010.

Last week, a source familiar with the selection process said the White House had narrowed the selection to three candidates: Srinivasan, Garland and Paul Watford, 48, a judge on the San Francisco-based 9th U.S. Circuit Court of Appeals.

Watford is an African-American and the U.S. Supreme Court has had only two black justices in its history.